The synthesis of early proteins from Chlamydia trachomatis serovar L2 was analyzed by two-dimensional gel electrophoresis. By pulse-label experiments, the synthesis of seven proteins was observed at 2 to 8 h postinfection before the major outer membrane protein was detected at 8 to 10 h after infection. The early proteins were synthesized throughout the 30-h period investigated, but the synthesis of three proteins of 75, 62, and 45 kilodaltons decreased from 26 to 30 h postinfection. Pulse-chase analysis showed that the signals from the same three proteins declined 26 to 30 h after infection. Three of the early proteins were identified as the S1 ribosomal protein, the GroEL-like protein, and DnaK-like protein, respectively.