Objective This study describes the development of a preliminary version of an instrument that attempts to assess the quality of reports of individualized homeopathic prescriptions in clinical trials and observational studies. Methods A multidisciplinary panel of 15 judges produced an initial version of the instrument through iterative Delphi rounds and pilot-tested the instrument on five clinical trials. Later they assessed, under blind conditions, the individualization quality of 40 randomly-selected research reports. The final version of the instrument included six criteria. These items were scored consistently by all the raters regardless of background. Results The instrument appeared to have adequate face and content validity, acceptable internal consistency or reliability (Cronbach's α 0.606 – 0.725), significant discriminant validity (F = 398.7; P < 0.000 1), moderate interrater reliability (Fleiss κ 0.533), agreeable test-retest reliability (Cohen's κ 0.765 – 0.934), moderate sensitivity (0.4; 95% confidence interval 0.253–0.566), and high specificity (1.0; 95% confidence interval 0.891–1.000). Conclusion The initial data suggest that this instrument may be a promising systematic tool amendable for further development.