Recently, there has been an increasing focus on the pursuit of targets considered to be less druggable that offer potential for development of promising new therapeutic agents for the treatment of diseases with large unmet medical need, particularly in the areas of oncology and virology. However, conducting drug discovery campaigns in "beyond rule of 5" (bRo5) chemical space presents a significant drug design and development challenge to medicinal chemists to achieve acceptable oral pharmacokinetics. Retrospective analysis of past successes and failures in drug discovery bRo5 may shed light on the key principles that contribute to the oral bioavailability of successful bRo5 compounds and improve the efficiency of drug design for future projects. We present here highlights and case studies of lessons learned from discovery of bRo5 compounds. A simple multiparametric scoring function (AB-MPS) was devised that correlated preclinical PK results with cLogD, number of rotatable bonds, and number of aromatic rings.