I
- Institute of Energy Professionals Africa (IEPA)
- Institute of Environmental and Recreation Management (IERM)
- Institute of Estate Agents of South Africa (IEASA)
- Institute of Fire Engineers South Africa (IFE)
- Institute of Global Dialogue (IGD)
- Institute of Information Technology Professionals South Africa (IITPSA)
- Institute of Internal Auditors South Africa (IIA SA)
- Institute of Inventors and Innovators (III)
- Institute of Loss Adjusters of Southern Africa (ILASA)
- Institute of Management Consultants and Master Coaches of South Africa (IMCSA)
- Institute of Marine and Environmental Law (IMEL)
- Institute of Market Agents of South Africa (IMASA)
- Institute of Marketing Management (IMM)
- Institute of Mine Surveyors of Southern Africa (IMSSA)
- Institute of Municipal Engineering of Southern Africa ()
- Institute of Municipal Engineering of Southern Africa (IMESA)
- Institute of Natural Resources (INR)
- Institute of Packaging South Africa (IPSA)
- Institute of People Management (IPM)
- Institute of Plumbing South Africa (IOPSA)
- Institute of Professional Engineering Technologists (IPET)
- Institute of Quarrying Southern Africa (IQSA)
- Institute of Retirement Funds Africa (IRFA)
- Institute of Risk Management South Africa (IRMSA)
- Institute of South African Municipal Accounting Officers (ISAMAO)
- Institute of Waste Management of Southern Africa (IWMSA)
- Institution of Certificated Mechanical & Electrical (ICMEES)
- Institution of Certificated Mechanical and Electrical Engineers, South Africa (ICMEES)
- Institution of Fire Engineers South Africa (IFE)
- Institution of Fire Engineers South African Branch (IFE)