Sharing the methods and results of clinical trials with full transparency is an ethical obligation for those involved in clinical research. However, a poor results reporting rate has been pointed out, with approximately half of the trial results not been reported. It has been suggested that one of the reasons behind this could be the influence of the sponsors that conduct the clinical trials. In our previous trend analysis on regenerative medicine for stroke, we became suspicious of the low result reporting rate of the gene and/or cell therapy trials. For this reason, a multivariate analysis using data from was performed to identify the factors affecting the low result reporting rate, expanding our study to four different kinds of neurological diseases and regenerative medicine as a treatment modality when small-molecule compounds and biologics were set up as controls in addition to the sponsor type factor. As a result, the following factors were identified as the independent causes of an increase in the low reporting results rate: Stroke (as disease area), trials completed between 2005 and 2007, clinical phases II and IV, and gene/cell therapy (as treatment modality). On the other hand, big pharmaceutical companies were identified as a factor that increased the reporting results. When we applied result reporting publications via PubMed as an index, our study data revealed that the following factors were not identified as the cause for a decrease in the reporting results rate: stroke (as disease area), trials completed between 2005 and 2007, and gene/cell therapy (as treatment modality). In this context, our findings indicate that gene/cell therapy has led to the suppression of the result reporting rate to ClinicalTrials.gov. This confirmed our initial suspicion of the low result reporting rate of gene/cell therapy trials. We believe that further studies are required to elucidate the factors affecting the result reporting rate from the perspective of disease area and treatment modality.