Background Dosage forms of oral medications are frequently modified in aged care facilities by crushing/splitting tablets or opening capsules to facilitate medication administration for residents with swallowing difficulties. These practices pose safety concerns including the risk of adverse events resulting from loss of dose during transfer and alteration in the rate of absorption. Objective To identify the incidence, methods, and appropriateness of oral dosage form modification practices in aged care facilities. Setting A purposive sample of four urban and regional aged care facilities in Queensland, Australia. Method The processes of modification of oral dosage forms were observed and video-recorded using an action camera placed on medication trolleys. Each video was then reviewed and the details of the medication modification processes were recorded in a data collection form. The appropriateness of the practices of dosage form modification was evaluated against existing national guideline (Australian Don’t Rush to Crush Handbook). Deviations from the instructions in the guideline were considered as inappropriate practice. Main outcome measure Incidence and characteristics of inappropriate modification of oral dosage forms. Results Oral dosage forms were modified in 25.7% of 810 observed medications. The most common methods of dosage form modification included crushing tablets with a manual crushing device (71.6%), cutting/splitting tablets (20.2%), and opening capsules (4.3%). According to the national guideline, 12.5% of the modification instances were inappropriate. Inappropriate practices were commonly associated with the suboptimal methods of medication preparation where medications were unsuitably modified, mixed, spilled, or incompletely dosed. Conclusion The modification of oral dosage forms seems a common practice in aged care facilities in Queensland. However, some of these modifications do not comply with the requirements of good practice according to existing guidelines. Healthcare workers in aged care facilities need to be supported and upskilled with effective training to promote the best and safest practices of ODF modification.