OBJECTIVE Only 53% and 63% of studies and clinical trials results presented at congresses are published. Company-sponsored trial results are being posted on publicly accessible Web sites. We analyzed the public availability (publication or posting on a Web site) rate, time to publication, and factors predicting public availability of results of studies sponsored by a pharmaceutical company. METHODS This was a retrospective cohort study analyzing all studies conducted by GlaxoSmithKline in Spain between 2001 and 2006. Initiation and completion were defined as first participant/first visit and last participant/last visit (or their equivalents). Papers published up to 31 March 2009 were considered. Logistic regression models were used to identify factors predicting public availability of results. RESULTS The cohort comprised 143 studies (94 clinical trials; of these, 87 were included in international products clinical development plans). Public availability rate was 80% (114/143) for all studies and 78% (73/94) for clinical trials; publication rates were 68% and 61%, respectively. The median time to publication for all studies and trials was 27.3 and 28.4 months, respectively. Study associated to a cancelled project was the only significant factor associated with lower publication rate for all studies [odds ratio (OR) 0.069; 95% confidence interval (CI) 0.02-024; p < 0.001) and trials (OR 0.075; 95% CI 0.016-0.343; p = 0.001) and a lower public availability rate (OR 0.052; 95% CI 0.007-0.382; p = 0.004) for trial results. Therapy area, sample size, positive trial results, duration of experimental phase, and being a clinical trial did not predict publication or public availability. CONCLUSIONS Eighty percent of studies included in this analysis are publicly available. Web site posting increases public availability rate of clinical trial results from 61% to 78%. Cancellation of projects is the single factor negatively influencing publication and public availability rates.