Three different sieve size fractions of ergot-containing biodegradable microcapsules were examined both in vitro and in vivo. The sieve sizes and average particle diameter, ( mu m), were: less than 45-75; 75-106; 106-177. These microcapsules contained ca. 9 percent drug and were produced from 50:50 poly(DL-lactide-co-glycolide) The objective was to determine the effect of particle size on in vivo and in vitro degradation rates. The microcapsules were injected into rat gastocnemius muscle and excised and examined at various time points up to 70 days. Over the microcapsule size ranges examined, minimal differences in the degradation properties were noted. 18 Refs.