The Inter-American Development Bank of Washington is lending Jamaica $27.3 million to improve roadways and health care in small rural towns.

The project is aimed at small towns that have a good economic base and agricultural potential, but need schools, health centers, roads and better drainage facilities.

Jamaica plans to fix 175 miles of access roads and 25 miles of rural roads. It will build a secondary school at Annotto Bay for 1,125 students and repair nine existing schools in eight other townships. The country also will construct four health-care facilities and improve drainage in seven towns.

All the townships selected for the project have less than 30,000 residents. Jamaica's Urban Development Corp., the executing agency for the loan, will encourage residents to properly dispose of trash and help maintain schools and health centers.

This project is the second stage of a program initiated in 1983 with two Inter-American bank loans that totaled $16.4 million.

The Inter-American Development Bank is also helping Venezuela fix its national highways with a $71.6 million loan.

Roads that have deteriorated from heavy traffic will be repaired. Workers also will repave the highways and build retaining walls, ditches and gutters.

The repairs may step up farm production and reduce congestion in the capital area by spurring development in other regions, the bank said.

Highways are the most important means of transportation in Venezuela, but only 33 percent of its highways are paved. Railroads are marginal, waterway shipments are limited to a few products, such as iron and bauxite, and air shipment is used for more expensive goods traveling long distances.

The bank's loan was extended over 20 years at an interest rate to be determined periodically.