The Grateful Dead's appearance at the Capital Centre last night was not your ordinary rock concert. The roads to the arena were lined with desperate fans offering as much as $100 a ticket, and inside the bootleg tapers raised a forest of hundreds of microphone stands, most of them with stereo capability. The packed house -- fully half of them dressed in tie-dye -- gave the musicians a roaring ovation as they tuned up in the dark before their first song.

The Grateful Dead are now celebrating their 20th anniversary. They have their limitations -- the lack of a real lead singer, the amorphousness of their beat, the insularity of their world view -- but they have developed such a distinctive sound that they can be compared only to themselves.

In that context, last night's show was a B-plus. It wasn't one of those memorable nights when everything clicks; neither was it one of those nights (so common a few years ago) when the tempos ooze and the vocals rasp. Riding the strength of their first-ever hit single and their fastest-selling album ever, the Grateful Dead displayed their strengths to best advantage.

Jerry Garcia kept his country-jazz guitar solos crisp, alert and inventive. In each song, the rhythm section patiently shifted its rumbling, tumbling momentum upward through gear after gear. The three-part bluegrass harmonies created a warm, resonant tone that none of the singers could produce alone.

Most impressive was the band's ensemble spirit, which spread contagiously to the crowd. The six musicians gave the impression of each playing free-form parts, all the while relying on their rapport to coalesce into a unified whole. Typical were songs like Garcia's "The Deal" or Bob Weir's "Sugar Magnolia," which sounded a bit loose and ragged at first but which pulled together for rousing finishes.

The band built the usually lazy "Sugaree" to a feverish pitch, and Garcia responded with solos that crystallized in tone even as they gathered speed. Weir belted out his 12-bar blues, "Lion's Den," with a passionate growl and then pitted his slide guitar broadside against Garcia's single-note precision. A bluesy reworking of the Dead's oldie "St. Stephen" led to a heated vocal duet between Garcia and keyboardist Brent Mydland on Steve Winwood's "Dear Mr. Fantasy."

The evening's low point came in the second set as Weir's gimmicky "Estimated Prophets" gave way to an indifferent "The Eyes of the World," which segued into a self-indulgent percussion jam, which in turn segued into a tedious, spacey guitar duet. By contrast, the biggest surprise was a strong version of Bob Dylan's "Desolation Row," which Weir sang in its entirety with effective understatement over a graceful country arrangement. The Grateful Dead return for sold-out shows at the Capital Centre tonight and tomorrow